1. Field of the Invention
The inventions relate to optical receivers and methods of operating optical receivers.
2. Discussion of the Related Art
In some optical communication systems, a coherent optical receiver has a local optical oscillator that is not phase locked to the received data-carrying optical carrier. In such optical receivers, the local optical oscillator still may have a frequency that is close to the center frequency of the data-carrying optical carrier. In particular, an intradyne optical receiver has a local optical oscillator whose frequency is closer to the center frequency of the data-carrying optical carrier than the bandwidth of the data-carrying optical carrier. In an intradyne optical receiver, such approximate frequency matching may be achieved, e.g., without a loop that feeds back information on the received data-carrying optical carrier. That is, the local optical oscillator of an intradyne optical receiver may be free running.